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Posted by Stateng on March 17, 2002 at 16:52:48:

In Reply to: Question on Horsepower posted by Dennis on March 16, 2002 at 01:35:42:

: While reading the book "Stationary Engineering" I came across the following sample test question.

: "A 50 HP motor runs at 75% efficiency. What watts per HP are being used?" There are 4 answers to chose from but this book doesn't give the correct answer.

: Can anyone tell me how to solve this question?

: All I know is that one HP is equal to 746 watts but I don't know where to go from there. Thanks.

Dennis

The 50 HP motor at full load uses (746X.50) = 37300 watts of input but the motor is only 75 % efficient there fore we are actually getting only (50x.75) =37.5 horsepower of work. Therefore the watt consumption per useful horsepower is (37300/37.5)=994.6 watts.